Redox-active polymers and their applications

ABSTRACT

The present invention is directed to a redox-active, conducting polymer energy storage system, said system including an electrode and a counter electrode, wherein the electrode comprises a first conducting polymer and the counter electrode comprises a second conducting polymer, wherein the first conducting polymer is doped by at least one or more first redox-active compounds and/or by a polymer and/or a co-polymer of the one or more first redox-active compounds and the second conducting polymer is doped by at least one or more second redox-active compounds and/or by a polymer and/or a co-polymer of the one or more second redox-active compounds, and wherein there is a potential difference between the dopant for the electrode and the dopant for the counter electrode. In one preferred embodiment, the first or the second redox-active compound is 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonate) (ABTS). In another preferred embodiment, an exemplary redox-active compound is a polymerizable derivative of ABTS or a polymer or co-polymer of this monomer.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. application Ser.No. 11/512,430, filed Aug. 29, 2006, and claims the priority of U.S.Provisional Application No. 60/712,724, filed Aug. 29, 2005, both ofwhich are hereby incorporated by reference herein.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

N/A

BACKGROUND OF THE INVENTION

The molecule 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS)is an important redox-active compound with broad chemical, material andbiomedical applications. For example, ABTS and its derivatives have beenused as the electrochromic component in smart windows,¹ as a chromogenicsubstrate in assays for enzymatic activity² and as a mediator forelectron transfer in bioelectrocatalysis.³ Interest in the use of ABTSin the bioelectrocatalytic reduction of oxygen to water has increasedprimarily because its redox potential is near that of oxygen undermildly acidic conditions.⁴

BRIEF SUMMARY OF THE INVENTION

The present invention provides both redox-active monomers andredox-active polymers polymerized therefrom. Preferably, theredox-active monomers of the invention can undergo radical initiatedpolymerization to form the redox-active polymers. Exemplary redox-activemonomers and polymers of the invention can comprise ABTS. The inventionalso provides methods of synthesis for the redox-active monomers andpolymers of the invention. Furthermore, the invention provides devicescomprising one or more the redox-active monomers and/or polymers of theinvention, which can be used in, for example, broad chemical, materialand biomedical applications.

Interest in redox-active polymers stems from their application inelectrochromic devices,⁵ biofuel cells⁶ and biosensors, all of whichrequire a high concentration of electron mediators that arenon-leachable.⁷ Employment of ABTS and its derivatives for such uses,however, has been limited to solution phase applications prior to thepresent invention. The development and synthesis of polymerizablederivatives of ABTS would enable the fabrication of composites thatpossess the redox and chromogenic properties of ABTS, but in anon-leachable, solid-phase form. Use of prior art versions of ABTS incomposites leads to leaching of the ABTS molecule from the compositeupon exposure to solvents, which results in the loss of the composite'sredox and chromogenic properties. In one aspect, the invention isdirected to the synthesis of polymerizable derivatives of ABTS asexemplary redox-active monomers of the invention and redox-activepolymers formed therefrom. These monomers and polymers can besynthesized according to the invention in a non-leachable, solid-phaseform.

In a preferred embodiment, the redox-active monomers of the inventionare derivatives of the ABT core of ABTS and are polymerizable through afunctional group, e.g., a vinyl functional group, that allows for theirradical initiated polymerization into redox-active polymers of ABTS.Monomers of the invention that are derivatives of ABTS are generallyreferred to as ABTS monomers. Exemplary functional groups can alsopermit co-polymerization (or even higher order) with other monomerscontaining similar functional groups that can be polymerizedconcurrently with the redox-active monomers of the invention. By thechoice of other functional groups or functional group substituents,monomers according to the invention can be polymerized into polymershaving specific properties, e.g., hydrophobic or hydrophilic properties,and the redox and chromogenic properties of the monomers can beparticularly prescribed. The invention also provides co-polymers basedon the redox-active monomers according to the invention.

ABTS redox-active monomers according to the invention can have thefollowing structure:

wherein

R₁ and/or R₁′ are selected from the group consisting of MeO, EtO, COF₃,SO₄H, SO3⁻, SO₃H, H, CHNO₄S₂F₃, C₅H₄N₂O₆S₂F₆, C₁₀H₁₀N₄S₂, CH₃, n-Bu, Cl,NH₂, EtN, Br, alkyl, ether, ester, sulfonate, ammonium, carboxylate,phosphonate and any combination thereof;

R₂ and/or R₂′ are selected from the group consisting of EtO, SO₃H, H,C₁₀H₁₀N₄S₂, CH₃, Cl, C₆H₁₄N₂S and any combination thereof;

R₃ and/or R₃′ are selected from the group consisting of CH₃, Cl, H andany combination thereof; and

R₄ and/or R₄′ are selected from the group consisting of CH₃, H, C₂H₅,C₄H₉, C₆H₅, C₈H₁₇C₂H₅S, C₃H₇S, C₄H₈Br, C₁₀H₂₃N, C₂₀H₂₁N₂, C₁₈H₂₅N₂,C₂₁H₂₃N₂, C₃₁H₂₉N₂O₂, C₂₂H₂₅N₄, C₂₀H₂₅N₂, C₃H₇OS, and any combinationthereof.

In general, the above structure (or monomeric unit) can be made to bepolymerizable through the presence of a functional group (which can bereferred to as a polymerizable function group), preferably, unsaturated,at R₁, R₁′, R₂, R_(2′), R₃, R₃′, R₄, R₄′ or combinations thereof. Theposition and types of functional groups (including other functionalgroups not specifically involved in polymerization) attached to aredox-active monomer according to the invention can also influence theproperties of the monomer and any polymer polymerized therefrom.

For example, the color of ABTS and its derivatives may be changed byadding different functional groups onto the ABT core. Exemplaryfunctional groups and their corresponding colors include 4,4′-dichlorofor black, 6,6′-dibromo for black, 6,6′-dinitro for brown, 4,4′-dimethylfor pink, 5,5′-dimethyl for brown, 6,6′-dimethoxy for black and6,6′-diethoxy for black. In one aspect, given the chemochromogenic andelectrochromogenic properties of ABTS and its derivatives, the abovestructure can be used as a chromogen.

The solubility of ABTS and its derivatives in water and other polarsolvents, e.g., alcohol, can also be increased by the addition ofdifferent types of functional groups at particular compound positions.For example, the solubility of the above structure in polar solvents canbe increased by adding, e.g., sulfonate, ammonium, carboxylate orphosphonate groups at R₁ and R₁′. The hydrophobic nature of the monomer,and, thus, its solubility in organic solvents, may be enhanced by theaddition of, e.g., alkyl, ether or ester groups at R₁ and R₁′.

In addition, R₁, R₁′, R₂, R₂′, R₃, R₃′, R₄′ and R₄ of the abovestructure may comprise reactive chemical functional groups (e.g.,carboxylic acids and their derivatives, amines and their derivatives)that would enable the coupling of biological molecules-of-interest(e.g., DNA, RNA, proteins, carbohydrates, lipids) or other compounds(e.g., pharmaceuticals, redox-active compounds, dyes).

Polymerizable functional groups that can be attached to a redox-activemonomer of the invention or any of R₁, R₁′, R₂, R₂′, R₃, R₃′, R₄, R₄′ orcombinations thereof in the above structure include, for example, thosein Table 1.

TABLE 1 Unsaturated carbon monomers including, but not limited to:Olefins, halo-olefins, dienes, acetylenes, styrenes, vinyl compounds andacrylic acids (including acrylics). Ring monomers including, but notlimited to: Cyclic ethers, lactones, lactams, cyclic amines, cyclicsulfides, cyclic carbonates, cyclic acid anhydrides, cyclic iminoethers,amino acid N-carboxy anhydrides, cyclic imides, phosphorus containingcyclic compounds, silicon containing cyclic compounds and cyclicolefins. Bifunctional monomers including, but not limited to: Phenols,melamines and ureas

diamines, dicarboxylic acids, hydroxy acids (including oxy carboxylicacid), amino acids (including amino carboxylic acid), diols,diisocyanates, sulfur containing compounds, phosphorus containingcompounds, aromatic ethers, dihalides (including dihalogenatedcompounds), aldehydes, diketones and carbonates (including carbonic acidderivatives). Other monomers including, but not limited to, anilines andsilane compounds.

The above functional groups are also described byhttp://polymer.nims.go.jp/guide/guide-eng/term_monomer.html#chap04.

Preferred ABTS monomers according to the invention have the followingstructure:

wherein either R₂ and/or R₃ comprises a carbon monomer functional groupas described above and wherein either R₁ and/or R₄ comprises ahydrophobic functional group such as, for example, hydrogen, alkyl,ether, ester, etc. or a hydrophilic functional group such as, forexample, sulfonate, ammonium, carboxylate, phosphonate, etc.

Described herein are the synthesis protocols for two monomer derivativesaccording to the invention comprising the ABT core of ABTS, namely,N-(3-methyl-3H-benzothiazol-2-ylidene)-N′-[3-(4-vinyl-benzyl)-3H-benzothiazol-2-ylidene]-hydrazine(sABT) and3-methyl-2-{[3-(4-vinyl-benzyl)-3H-benzothiazol-2-ylidene]-hydrazono}-2,3-dihydro-benzothiazole-6-sulfonicacid (sABTS). These compounds can be polymerized or co-polymerized withother monomers in order to tune the physical properties of the resultinglow potential, electrochromic, redox-active polymer.

Monomers and polymers, or co-polymers, according to the invention wouldfind use as the active components of a redox-active, chromogeniccomposite in applications such as the following: (i) cathode of abiofuel cell; (ii) electron mediator of an air-breathing biocathode;(iii) sensing element of a device to test for the presence of laccase ororganisms that produce laccase (an enzyme whose presence is indicativeof, e.g., contaminated wine or wine products); (iv) sensing element of adevice to measure the presence of oxygen or pH of a solution; and (v)display technologies, such as those using suspended particle devices(SPDs). For example, any present application of a commercial,conventional form of ABTS (e.g., enzyme assays, biosensors,electrochromic devices) may be improved by using, instead, a polymer ofABTS according to the invention (polyABTS), preferably, in anon-leachable, solid-phase form, which has been synthesized from apolymerizable, low potential ABTS monomer according to the invention(i.e., a monomer having a halfwave potential, E_(1/2), >500 millivoltsvs. a saturated calomel electrode).

Thus, in another aspect, the invention is directed to a redox-active,conducting polymer energy storage system, e.g., a battery or acapacitor, comprising any conducting polymer as the basis for anelectrode or counter electrode, e.g., the anode or cathode,respectively, wherein, for example, the conducting polymer of theelectrode is doped with a first redox-active compound, wherein, forexample, the conducting polymer of the counter electrode is doped with asecond redox-active compound and wherein there is a potential differencebetween the dopant for the electrode and the dopant for the counterelectrode.

Exemplary conducting polymers include organic polyheterocyclics, such aspolypyrrole, polythiophene, polyaniline and their derivatives. Oneadvantage of using electrically conducting polymers is that suchmaterials can be modified with charged “dopants” tailored to specificapplications. For example, positively or negatively charged ions can beused as a dopant for conducting polymers. In one aspect, the monomersfor such polymers can be electropolymerized anodically to generatepolarons and subsequently bipolarons, with, for example, one positivecharge for every three to four monomeric units. For example, in the caseof pyrrole, to compensate for the positive charge that develops alongthe polymeric backbone, a counter anion dopant becomes electrostaticallybound to the polymer during electrodeposition, such as represented by[(C₄H₆N)⁺ _(3 or 4)(X⁻)]_(n). If the counter anion is large orpolyanionic, it can actually become physically entangled and immobilizedwithin the conducting polymer or its associated “matrix.”

By immobilizing monomers and/or polymers according to the invention,such as, for example, ABTS monomers and/or polymers polymerizedtherefrom, in a conductive polymer matrix disposed on an electrodesurface, one can significantly increase current flow and the energy thatcan be stored within the polymer matrix. Polymers according to theinvention are not just charged but are also fully redox-active.Redox-active polymers of the invention can be used in conjunction withredox-active enzymes. For example, low potential redox-active polymerscan be useful at voltages near that of oxygen, making such polymersideal for use with redox-active enzymes. Still, other redox-activepolymers of the invention can be used at higher potentials.

In another aspect, the invention is directed to a handheld biosensorelectronic device that uses a polymer according to the invention, suchas polyABTS, as the active material for detecting, e.g., the level oflaccase in a sample. Such detections using a biosensor electronic deviceof the invention are preferably based on a biochemical reaction betweenpolyABTS and laccase in the presence of oxygen. For example, detectioncan relate to the electrochemical reduction of the polyABTS radical.More broadly, the presence of any enzyme that could use any redox-activepolymer according to the invention as a substrate or any chemical thatwould oxidize a polymer according to the invention to its radical form,either in solution or in the air, could be detected using a biosensorelectronic device of the invention.

In another aspect, the invention is directed to an air-diffusionbioelectrocatalytic cathode or cathode system operable in humidified airor humidified oxygen. In a preferred embodiment, a cathode systemaccording to the invention comprises a polymer composite featuringpolypyrrole embedded with laccase and polyABTS as thebioelectrocatalytic material of the system. Broadly speaking, anyredox-active monomer or polymer according to the invention can be usedas the bioelectrocatalytic material of a cathode system as describedherein. In general, polymer based systems would usually be preferableover monomer based systems as leakage of a monomer or its associatedmediator would reduce the lifetime of the cathode. Moreover, anyconducting polymer such as, for example, polyaniline and its derivativescan fulfill the role described herein for polypyrrole.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the invention will be apparent from thefollowing description of the preferred embodiments thereof and from theclaims, taken in conjunction with the accompanying drawings, in which:

FIG. 1 shows exemplary synthetic routes to two ABTS monomers of theinvention;

FIG. 2 shows cyclic voltammograms (CVs) of commercially available ABTSand of ABTS monomers and poly ABTS according to the invention.Commercially available ABTS (closed circles), sABT monomer (opencircles), sABTS monomer (solid line) and film of polyABTS (opentriangles);

FIG. 3 shows a spectroelectrochemistry evaluation of a polyABTS/ITOelectrode according to the invention immersed in 0.2 M KCl. The spectracorrespond to before (solid line) and after (dotted line) application ofpotential. Inset: UV-Vis spectra of sABT (open circles), sABTS (solidline) and ABTS (closed circles) in DMSO;

FIG. 4 shows linear sweep voltammograms (LSVs) of a polyABTS/glassycarbon electrode according to the invention. The electrode was immersedin 0.2 M KCl purged with either nitrogen or oxygen (solid line); orimmersed in 0.2 M sodium acetate buffer (pH 4) containing 1 mg/mllaccase and purged with nitrogen (open circles) or oxygen (closedcircles). The scan rate for all LSVs was 1 mV s⁻¹;

FIG. 5 shows an energy storage system of the invention (a battery) basedon a pPy[IC] anode and pPy[ABTS] cathode;

FIG. 6 illustrates that current measured at an electrode coated withpolyABTS of the invention is due to laccase catalyzed oxidation of ABTSto ABTS. with concurrent reduction of oxygen to water;

FIG. 7 shows the concentration of laccase in a sample of red wine as afunction of current density;

FIG. 8 shows the relationship among current, time and number of coulombspassed during the electrodeposition of a polypyrrole/ABTS/laccase (PAL)system according to the invention on carbon paper;

FIG. 9 shows a scanning electromicrograph (SEM) of a PAL electrodesystem on Toray carbon paper;

FIG. 10 a shows current density versus potential plots obtained fromdifferent hydrogen/oxygen fuel cells according to the invention withdifferent cathodes: PAL=with laccase, PA without laccase;

FIG. 10 b shows the corresponding potential versus power density plotsfor the fuel cells of FIG. 10 a; and

FIG. 11 shows a suspended particle device (SPD) of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION

In one aspect, the invention provides redox-active monomers of ABTS andits derivatives capable of polymerizing into a redox-active polymer.Preferably, monomers of the invention includeN-(3-Methyl-3H-benzothiazol-2-ylidene)-N′-[3-(4-vinyl-benzyl)-3H-benzothiazol-2-ylidene]-hydrazine(sABT) and3-Methyl-2-{[3-(4-vinyls-benzyl)-3H-benzothiazol-2-ylidene]-hydrazonol}-2,3-dihydro-benzothiazole-6-sulfonicacid (sABTS). These monomers are also referred to as polymerizablederivatives of ABTS.

The examples herein are provided to illustrate advantages of theinvention, including those that have not been previously described, andto further assist a person of ordinary skill in the art with using themonomers, polymers, co-polymers and devices of the invention. Theexamples can include or incorporate any of the variations or inventiveembodiments as described herein. The embodiments that are describedherein also can each include or incorporate the variations of any or allother embodiments of the invention. The following examples are notintended in any way to otherwise limit or otherwise narrow the scope ofthe disclosure as provided herein.

Exemplary Approaches to Synthesis and Products therefrom

Example of synthesis of sABT, sABTS and polyABTS of the invention aswell as characterization of the monomers and polymers of the invention:

In another aspect, the invention provides a synthetic route forsynthesizing polymerizable derivatives of ABTS. An exemplary syntheticroute of the invention is shown by the five step route of FIG. 1. Thefirst four steps result in a common intermediate 4 that can be used tomanipulate the solubility of the monomer end products and thehydrophobicity or hydrophilicity of their corresponding polymers.Reaction of 4 with, for example,3-methyl-benzothiazolinone-(2)-hydrazone (METH) results in a hydrophobicproduct (sABT) whereas reaction of 4 with 3-methyl-6-(Msulfonate)-benzothiazolinone-(2)-hydrazone (MBTHS) results in thehydrophilic product (sABTS). Both products can yield redox activepolymers that are hydrophobic, hydrophilic, or amphiphilic depending onthe ratio of sABT to sABTS.

The first step in the synthetic sequence reacts 2-benzothiazolinone with4-vinylbenzyl chloride under basic conditions using methods similar tothat described by J. D'Amico et al. to yield the N-styryl substitutedbenzothiazolinone 1 as a white crystalline solid in a yield range from,for example, 91 to 93%.⁸ Optimal reactions conditions were found at 60°C. for 1 hour in a dimethylformamide (DMF) solution containing 9 molar(M) potassium hydroxide (KOH). Higher temperatures or longer reactiontimes led to more side products and a lower yield.

Hydrolysis of benzothiazolinone⁹ and thiazolinone¹⁰ can be accomplishedusing different approaches. The hydrolysis of 1 was accomplished bypurging a mixture of methanol and water containing a high concentrationof KOH with nitrogen to give an aminothiol product. Chromatographicisolation of the aminothiol product from several side products, however,proved difficult. Therefore, the hydrolysis reaction was performed inthe presence of oxygen to give the corresponding disulfide 2 in, forexample, 53-55% yield. The disulfide, which is a yellow crystallinesolid, is easier to isolate because its retardation (Rf) value is higherthan 1 or the aminothiol product obtained in the absence of oxygen. Boththe aminothiol product or 2 will react with carbon disulfide whenrefluxed in a mixture of ethanol and sodium hydroxide (NaOH) to give 3as a white crystalline solid.¹¹ Choosing the disulfide product insteadof the aminothiol product simplified the isolation process to give 3 in,for example, 82-84% yield. Diethyl ether was the solvent of choice forextraction of the 3 from the reaction mixture.

Benzothiazolinone or thiazolinone are known to react with thecorresponding benzothiazolinethione or thiazolinethione via phosphoruspentasulfide thiation reaction or Lawesson's reagents without anintermediate hydrolysis step.¹² Compound 1, however, does not react withthose reagents using either method. Moreover, the Rf values of bothbenzothiazolinone and benzothiazolinethione are identical, making itdifficult to isolate the product from the starting material using liquidchromatography.

Sulfonation of MBTH, available from Aldrich Chemical Co., Milwaukee,Wis., yields MBTHS according to U.S. Pat. No. 5,989,845, herebyincorporated by reference herein.¹³ Both MBTH and MBTHS react with 4 togive the respective exemplary monomers of the invention, sABT and sABTS(FIG. 1).

Methylation of 3 was achieved with dimethyl sulfate¹⁴ as all attempts tomethylate 3 with methyl iodide were unsuccessful. The derivatives ofhydrazone, MBTH and MBTHS, were reacted with the methylated product 4 toobtain sABT (50%) and sABTS (63%) respectively, without furtherisolation.¹⁵ Both sABT and sABTS are white powders. It should be notedthat the sodium salt of sABTS is difficult to dissolve in any solvent.Therefore, this product was prepared for chromatographic isolation andpolymerization by washing with 1 M hydrochloric acid (HCl). Subsequentto chromatographic isolation, the purified product was neutralized withan organic base (e.g., tetrabutylammonium hydroxide) to obtain a productthat exhibits good solubility in both organic solvents and water forsubsequent polymerization.

The tetrabutylammonium salt of sABTS was polymerized in ethanol for 1day at 65° C. in the absence of oxygen using2,2′-azo-bis(isobutyronitrile) (AIBN) (50:1) as the radical initiator.Subsequently, a solution containing polyABTS of the invention (˜28micromole, μmol, of the sABTS monomer, as calculated from the absorptionspectrum using the extinction coefficient of sABTS) was dried on thesurface of a rotating electrode (with a diameter of 4 millimeters, m)for cyclic voltammetry and bioelectrocatalysis experiments. A secondsolution containing polyABTS of the invention (˜56 μmol of the sABTSmonomer) was dried on the surface of an indium-tin oxide (ITO) electrode(with a surface area of 1 centimeters squared, cm²) for electrochromicexperiments.

Values for E_(1/2) of sABT, sABTS (both of the invention) and ABTS(commercially available) were obtained from the CVs shown in FIG. 2. Theconcentration of all three monomers was 2.5 mM, the electrolyte was 0.1M tetrabutylammonium hexafluoroborate in DMSO. Also shown is the CV ofan electrode coated with polyABTS immersed in an aqueous solution of 0.2M KCl. The scan rate was 10 mVs⁻¹ for all CVs. All potentials arereported versus SCE. For sABT, E₁₁₂ is 613 millivolts (mV) whendissolved in a dimethyl sulfoxide (DMSO) solution containing in 0.1 Mtetrabutylammonium hexafluoroborate. Under identical conditions, E_(1/2)of sABTS is 620 mV. The peak to peak separation of 76 mV for sABT and 78mV for sABTS indicate-reversible electrochemical reactions.¹⁶ Thediffusion coefficients of sABT and sABTS are 1.21×10⁻⁶ cm²s⁻¹ and8.1×10⁻⁷ cm²s⁻¹, respectively. For comparison, the value for E₁₁₂ ofABTS (commercially available) is 587 mV in DMSO and 440 mV in sodiumacetate buffer (pH 4).⁴ The diffusion coefficient of ABTS in DMSO is1.39×10⁻⁶ cm²s⁻¹ and in sodium acetate buffer (pH 4), the value is3.22×10⁻⁶ cm²s⁻¹. Also shown in FIG. 2 is the cyclic voltammogram of afilm of polyABTS prepared by drying a drop of a 25 μmol solution ofpolyABTS on a glassy carbon electrode. E_(1/2) of the polyABTS of theinvention film is 500 mV in 0.2 M potassium chloride (KCl) solution,which is 120 mV negative to that of its monomer in DMSO. The peak topeak separation is 168 mV indicating poor self-exchange kinetics in apure film of polyABTS.¹⁷

The method of Nicholson was used to determine the rate constant (k_(h))for heterogeneous electron transfer between a glassy-carbon electrodeand the polymerizable monomers of the invention.¹⁸ For sABT,k_(h)=1.47×10⁻³ cms⁻¹ and for sABTS, k_(h)=2.18×10⁻³ cms⁻¹. Forcomparison, k_(h)=2.02×10⁻³ cms⁻¹ for ABTS in 0.1 M tetrabutylammoniumhexafluoroborate DMSO solution, or 4.54×10⁻³ cms⁻¹ in sodium acetatebuffer (pH 4).

The compound, N,N′-Bis-(3-methyl-3H-benzothiazole-2-ylidene)-hydrazine(mABT), has been used as the electroactive component in anelectrochromic device.¹ Both mABT and sABTS have similar chemicalstructures, however, sABTS possesses an N-styryl group to render themonomer polymerizable and a sulfonate group to make it and itscorresponding polymer water soluble. Shown in FIG. 3 are theultraviolet-visible (UV-Vis) spectra of an ITO electrode coated with afilm of polyABTS of the invention (˜56 μmol sABTS) while immersed in anaqueous solution of 0.2 M KCl. Spectra correspond to the film before(solid line) and after (dotted line) poising the electrode at 600 mV for10 seconds. Application of an oxidizing potential converts polyABTS(transparent in the visible region of the absorption spectrum) topolyABTS.⁺ of the invention, which is blue-green in color.

Shown in the inset of FIG. 3 are the UV-Vis spectra of 20 micromolar(μm) solutions of sABT, sABTS and ABTS in DMSO. Both sABT and sABTS haveabsorption peaks at ˜255 nanometers (nm), which corresponds toelectronic transitions in the styrene ring, and at ˜340 nm, whichcorresponds to electronic transitions in the conjugated system thatinclude the four nitrogen atoms. This absorption band is observed in theabsorption spectrum of commercial ABTS and therefore confirms thepresence of the same chromophore in both the sABT and sABTS monomers ofthe invention. The extinction coefficient of the reduced forms of sABTand sABTS dissolved in DMSO were determined to be 3.06×10⁴ M⁻¹cm⁻¹ at338 nm and 2.96×10⁴ M⁻¹cm⁻¹ at 341 nm, respectively. The extinctioncoefficient of ABTS at 340 nm in 0.2 M sodium acetate buffer (pH 4) hasbeen previously reported to be 3.45×10⁴ M⁻¹cm¹.⁴ Similar to polyABTS, acolor change is observed upon electrochemical oxidation of solutionscontaining the monomers sABT, sABTS, and ABTS (data not shown).

PolyABTS of the invention is also used to facilitate electron transportbetween the cathode of a biofuel cell and the active site of laccase inorder to generate electrical power.⁴ Shown in FIG. 4 are LSVs thatdemonstrate polyABTS of the invention participates in thebioelectrocatalytic reduction of oxygen to water. The LSVs werecollected under four different conditions: a polyABTS-coated electrodewas immersed in 0.2 M KCl that was purged with either 1) nitrogen or 2)oxygen; or the polyABTS-coated electrode was immersed in 0.2 M sodiumacetate buffer (pH 4) containing 1 milligram per milliliter (mg/ml)laccase that was purged with either 3) nitrogen or 4) oxygen. In theabsence of oxygen or laccase or both, reductive current is not observed.This result indicates that polyABTS itself does not catalyze theelectrochemical reduction of oxygen. When dioxygen and laccase are bothpresent, however, reductive current is observed. It should be noted thatreductive current is not observed at an uncoated electrode in thepresence of both dioxygen and laccase. These results confirm thatpolyABTS of the invention facilitates the transport of electrons fromthe working electrode to the active site of laccase in solution and alsoconfirm that polyABTS can be used in electrochemical sensors such as,for example, the handheld biosensor electronic device of the inventionthat detect dioxygen or laccase. In addition to a biosensor electronicdevice, the invention also provides other electrochemical sensors basedon the results of FIG. 4 that comprise polyABTS according to theinvention.

Examples of Co-Polymers According to the Invention:

The hydrophobic/hydrophilic characteristics of polyABTS of the inventioncan be varied with the choice of monomer functional groups and/or byco-polymerization with different monomers.

Two versions of polyABTS co-polymer of the invention have beensynthesized as described herein.

(1) Synthesis of a poly-ABTS-co-acrylate sodium salt (pAA) having thefollowing structure:

wherein m and n are integers and can be the same or different.

A polymerizable derivative of ABTS of the invention was synthesizedaccording to the method described above but modified as follows:

0.2 millimoles (mmol) of ABTS monomer,3-methyl-2-{[3-(4-vinyl-benzyl)-3H-benzothiazol-2-ylidene]-hydrazono}-2,3-dihydro-benzothiazole-6-sulfonatetetrabutyl-ammonium,and 0.2 mmol acrylic acid were dissolved in 0.5 ml ethanol with 4 μmolAIBN as an initiator. After purging with nitrogen for 30 minutes in icedwater, the reaction was heated and stirred at 65° C. for 1 day. Aftercooling the reaction, a cation exchange was performed on the polymerproduct, converting it into sodium salt. The product was dialyzed in amembrane with a 3,000 molecule weight cut-off.

(2) Synthesis of a poly-ABTS-co-vinyl imidazole sodium salt (pAVI)having the following structure:

wherein m and n are integers and can be the same or different.

A polymerizable derivative of ABTS of the invention was synthesizedaccording to the method described above, but modified as follows:

0.2 mmol of ABTS monomer,3-methyl-2-{[3-(4-vinyl-benzyl)-3H-benzothiazol-2-ylidene]-hydrazono}-2,3-dihydro-benzothiazole-6-sulfonatetetrabutyl-ammonium,and 0.2 mmol 1-vinyl imidazole were dissolved in 0.5 ml ethanol with 4μmol AIBN as an initiator. After purging with nitrogen for 30 minutes iniced water, the reaction was heated and stirred at 65° C. for 1 day.After cooling the reaction, a cation exchange was performed on thepolymer product, converting it into sodium salt. The product wasdialyzed in a membrane with a 3,000 molecule weight cut-off.

Exemplary Devices and Aspects of the Invention

Redox-active, conducting polymer energy storage system of the invention:

An exemplary energy storage system of the invention comprising twoconducting polymer electrodes incorporated with different electroactivedopants was developed. Polypyrrole (pPy) was used as the conductingpolymer with indigo carmine (IC) (to form pPy[IC]) and 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) (to form pPy[ABTS]) asdopants. This example describes a redox-active conducting polymerbattery, pPy[IC]|pPy[ABTS], in which the redox activity of the system isbased on the faradaic reactions of the dopants. In contrast,conventional batteries^(19,20) or electrochemical capacitors²¹ use theredox properties of or doping/dedoping of the conducting polymers forenergy storage.

An ABTS dopant of a conductive polymer in the energy storage system ofthe invention can be an ABTS monomer or polymer of the invention as wellas a conventional form of ABTS. The polymeric form is preferred as itwill be less likely to leach away from the conducting polymer matrixover time.

The pPy[IC]|pPy[ABTS] showed dramatically enhanced performance at highpower density (energy density, ED, equal to 8 watt-hours per kilogram,Wh kg⁻¹, at a power density, PD, of 10² to 10⁴ watts per kilogram, Wkg⁻¹). The characteristic performance comes from the combination ofmerits of batteries and electric double layer capacitors (EDLC). Theprinciple of energy storage is based on faradaic processes of redoxdopants (battery-like), but the electrochemical reactions are verysurface-confined without diffusion of the electroactive materials.Instead, the counter-ions in electrolytes neutralize the charge ofelectrodes (EDLC-like). The porous structure of the conducting polymerenables the access of counter ions to the dopants giving high surfacearea. Also, the conductively polymeric matrix provides electricallyconducting environments leading to enhanced electron transfer betweenbase electrodes and electroactive dopants.

Dopants IC and ABTS can have the following structures:

The cationic charge that develops in polypyrrole during theelectropolymerization of pyrrole requires an influx of anions from theelectrolyte to maintain charge neutrality.²² The above structures ofeach dopant (IC or ABTS) include two sulfonate substituents, whichconfer anionic character to these compounds in both their oxidized andreduced forms. Both IC and ABTS exhibit reversible redox chemistry at 52mV and 570 mV (all potential is reported versus silver/silver-chloride,Ag/AgCl, in this work), respectively, in a supporting electrolyte of 0.2M HCl, pH 1. Because of these two characteristics, anionic character andreversible redox chemistry, both compounds are attractive for their useas anionic dopants in the conductive form of polypyrrole. Dopantsincorporated in the conducting polymer on both positive and negativeelectrodes are required to be anionic and to show completely reversibleand fast faradaic reactions. In addition, the faradaic reaction ofdopants should not affect the properties of the conducting polymermatrix into which the dopants are incorporated. The larger the potentialdifference between the dopants for the positive and the negativeelectrode the higher the energy density in the battery. Consequently, itis better to use dopants that have a more positive redox potential forthe positive electrodes and a more negative redox potential for thenegative electrodes. The conducting polymer matrix and electrolytesshould be chosen by considering the redox potential of the dopants.

Doped polypyrrole was electrodeposited on a glassy carbon in an aqueoussolution of 200 mM pyrrole and 25 mM dopant (either IC or ABTS) bysweeping the potential between 0 and 650 mV for 40 cycles at 100 mV s⁻¹.Increases in current during electrodeposition were observed for bothdopants as the number of cycles increased, indicative of the formationof conductive films and incorporation of dopants into the conductingpolymer. Dark blue films were deposited. Based on elemental analysis,the ratio of pyrrole subunits to IC or ABTS dopants in polypyrrole wasestimated at 10:1, giving one positive charge for every five subunits ofpyrrole.

CVs of both pPy[IC] and pPy[ABTS] showed reversible redox behavior atthe same potentials as those of IC and ABTS in solution respectively.Thus, incorporation of IC or ABTS into polypyrrole does not affect theiraverage redox potential. Accordingly, a rechargeable battery of theinvention can be fabricated with pPy[IC] and pPy[ABTS] because thesematerials possess properties that are important to battery technology.First, both pPy[IC] and pPy[ABTS] exhibit reversible redox behavior atdifferent potentials. Second, the concentrations of IC and ABTS inpPy[IC] and pPy[ABTS] are high, allowing for high faradaic currents.Third, concentration overpotentials associated with a mass-transferlimited reaction is circumvented by confinement of the redox-activemolecules to the surface of the electrode. Thus, the rate of electrontransfer between the electrode and IC in pPy[IC] or ABTS in pPy[ABTS] isfast compared to IC or ABTS in solution. The first property is requiredfor a rechargeable battery and the second property affords a batterywith high energy density. The third property guarantees a battery withgood performance characteristics at fast discharge rates. Shown in FIG.5 a is a schematic diagram of the principle of a battery of theinvention using pPy[IC] as the anode and pPy[ABTS] as the cathode. Aschematic diagram of such a battery of the invention is given in FIG. 5b. During charging, the IC in pPy[IC] is reduced at 52 mV with protonsfrom the electrolyte at the anode. Simultaneously, the ABTS in pPy[ABTS]is oxidized to the radical cation at 570 mV with chloride anions fromthe electrolyte maintaining charge neutrality at the cathode. Duringdischarge the reverse reactions proceed at both electrodes respectively.

Based on the values of each electrode (Table 2), the theoreticalcapacity of a battery consisting of polypyrrole doped with IC and ABTSis estimated at 54 coulombs per gram (C g⁻¹) or 15 milliampere hours pergram (mAh g⁻¹). The theoretical capacity of this battery is one-sevenththe capacity of a lithium ion battery composed of a lithiated graphite(LiC₆) anode and a LiMn₂O₄ cathode (˜100 mAh g⁻¹).

TABLE 2 Electrochemical properties of redox units dissolved in solution(soln) and doped into films of polypyrrole with micro-coulombs as μC. ICABTS soln pPy[IC] soln pPy[ABTS] k° (cm sec⁻¹) × 7.9 26 15 9.1 10³ Q(μC) 2.2 85 1.6 84 Conc. (mM) C_(max) < 50 C_(film) = 1500 C_(max) < 100C_(film) = 2900 Capacity (C g⁻¹) — 170 — 80

Exemplary Biosensor of the Invention:

Oxidases such as laccase are secreted by the grey mold Botrytis cinerea.Contamination of grapes with Botrytis cinerea is an economical nightmarefor more than one million winemakers around the world because laccasecatalyzes the oxidation of antioxidants in wine such as polyphenol.Polyphenols contribute to the color, smell and taste of red wines andtherefore, are the most important components in red wine. Moreover, itis believed that polyphenols in red wine reduce the risk of heartdisease, stroke and cancer, with possible beneficial effects formuscular degeneration and Alzheimer's disease. When polyphenols areoxidized by laccase, however, they lose their antioxidant properties. Inaddition, when laccase is present, the color of wine turns from red tobrown, which is accompanied by an unpleasant smell and taste.Consequently, winemakers seek to detect the presence of laccase beforethey begin the fermentation process. Currently, winemakers send samplesof their wine to outside laboratories to test for the level of laccasein the wine. Typical costs are $50 per sample and testing takes at leasttwo days. Another aspect of the invention is a handheld electronicdevice that uses a polymer according to the invention, such as polyABTS,as the active material for detecting the level of laccase in a sample.This detection is based on a biochemical reaction between polyABTS andlaccase in the presence of oxygen, which can be detectedelectrochemically by the reduction of the polyABTS radical. The level oflaccase can be measured in 10 minutes, and, thus, this device would beuseful, e.g., to winemakers who wish to make in-house measurements ofthe level of contamination of all materials used at any point in thewinemaking process.

An exemplary device according to the invention was prepared as describedby the following:

An ABTS monomer{3-methyl-2-{([3-(4-vinyl-benzyl)-3H-benzothiazol-2-ylidene]-hydrazono}-2,3-dihydro-benzothiazole-6-sulfonatetetrabutyl-ammonium} (0.4 mmol) was dissolved in 1 ml ethanol/water (1to 1 ratio) with 0.02 mmol of the radical initiator AIBN. After purgingthe reaction mixture with nitrogen for 30 minutes while jacketed withiced water, the reaction was heated and stirred at 65° C. for 0.1 day.After cooling the reaction, the polymer product (polyABTS of theinvention) was converted to a lithium salt via cation exchange. Theproduct subsequently was dialyzed in a membrane with a molecular weightcut-off of 3,000.

After depositing a solution of polyABTS of the invention onto an ITOelectrode, the electrode was immersed in a solution of red wine withvarying concentrations of laccase. A potential was applied to theelectrode (100 mV versus SCE) and after 10 minutes, the value of currentwas measured.

Shown in FIG. 6 is a schematic that illustrates the operating principleof the exemplary device of the invention. An electrode is coated withpolyABTS. This material functions as a substrate to laccase. Whenlaccase and oxygen are present, laccase will catalyze the oxidation ofthe ABTS subunits in polyABTS to their radical form (ABTS). Oxidation offour equivalents of ABTS to ABTS. results in the reduction of all fourcopper (Cu) (II) ions in the active site of laccase to Cu (I) ions whereupon binding, one equivalent of dioxygen is reduced to two equivalentsof water. Thus, the active site of laccase is, returned to its restingstate (i.e., 4×Cu (II) ions). For bioelectrocatalysis to continue, theABTS. subunits in polyABTS must be reduced at the electrode to giveABTS. The reduction of ABTS. to ABTS by the electrode results in ameasured current, which can be correlated to the concentration oflaccase in solution. For example, if the concentration of laccase insolution is increased, the amount of ABTS oxidized to ABTS. increases ina given period of time, and, therefore, the amount of current requiredto reduce the greater quantity of ABTS. back to ABTS increases. Thethermodynamic driving force associated with the bioelectrocatalyticreaction described herein is shown on the right in FIG. 6.

As described by the following, the response of a polyABTS/ITO electrodeto changes in the concentration of laccase in red wine was tested.

An aqueous solution of polyABTS is deposited onto an ITO electrode andallowed to dry. After drying, the polyABTS/ITO electrode is immersed inred wine (pinot noir) containing laccase (from Trametes versicolor) atseveral different concentrations (0, 0.1, 0.5, 1, 2 units/ml). ThepolyABTS/ITO electrode and platinum gauze are connected to apotentiostat as working electrode and counter electrodes, respectively.A SCE is used as the reference electrode. A potential of 100 mV isapplied to the polyABTS/ITO electrode and after 10 minutes, the currentis recorded. The results are shown in FIG. 7.

Other exemplary uses for a biosensor according to the invention include,but are not limited to, incorporation in those assays and devicesindicated in Table 3. Broadly speaking, the presence of any enzyme thatcould use ABTS as a substrate or any chemical that would oxidize ABTS toits radical form, either in solution or in the air, could be detectedusing a device of the invention. The above example of a handheldbiosensor electronic device is merely one type of device contemplated bythe present invention. A biosensor of the invention can also be used todetect the presence of such exemplary enzymes as bilirubin oxidase,ceruloplasmin, ascorbate oxidase or copper oxidases as well as anyenzyme capable of reducing oxygen to water or to peroxide.

TABLE 3 Prior art assays and devices providing exemplary use for devicesand methods according to the invention  1. Potentiometric determinationof glucose in blood samples. (Borrajero, M., et al., Rassegna Chimica(1991), 43(2), 61-3)  2. HRP/[Zn—Cr-ABTS] redox clay-based biosensor:design and optimization for cyanide detection. (Shan, Dan, et al.,Biosensors & Bioelectronics (2004), 20(2), 390-396)  3. Sixspectroscopic methods for detection of oxidants in urine: Implication indifferentiation of normal and adulterated urine. (Paul, Buddha D.,Journal of Analytical Toxicology (2004), 28(7), 599- 608)  4.Application of the 2,2′-Azinobis(3-ethylbenzothiazoline-6-sulfonic acid)Radical Cation Assay to a Flow Injection System for the Evaluation ofAntioxidant Activity of Some Pure Compounds and Beverages. (Pellegrini,Nicoletta, et al., Journal of Agricultural and Food Chemistry (2003),51(1), 260- 264)  5. Pseudoperoxidase activity of myoglobin: kineticsand mechanism of the peroxidase cycle of myoglobin with H2O2 and2,2-azino-bis(3-ethylbenzthiazoline-6-sulfonate) as substrates.(Carlsen, Charlotte, et al., Journal of Agricultural and Food Chemistry(2003), 51(19), 5815-5823)  6. Application of a New Color DetectionBased Method for the Fast Parallel Screening of DeNOx Catalysts. (Busch,Oliver, et al., Journal of the American Chemical Society (2002),124(45))  7. New methods for the determination of chlorine species indrinking water. (Nowack, Bernd, et al., Proceedings - Water QualityTechnology Conference (1999), 1145-1161)  8. Enzymatic Determination ofMethanol with Alcohol Oxidase, Peroxidase, and the Chromogen 2,2′-Azinobis(3-ethylbenzthiazoline-6-sulfonic acid) and Its Application tothe Determination of the Methyl Ester Content of Pectins. (Mangos,Thomas, et al., Journal of Agricultural and Food Chemistry (1996),44(10))  9. Evaluation of the enzymic assay of blood ethanol with2,2′-azino-di(3-ethylbenzthiazoline-6- sulfonate) (ABTS) as chromogen.(Stojanov, Marina, et al., Acta Pharmaceutica (Zagreb, Croatia) (1992),42(1), 69-75.) 10. Detection of hydrogen peroxide produced bymicroorganisms on the ABTS peroxidase medium. (Mueller, Hans E., et al.,Zentralblatt fuer Baketeriologie, Mikrobiologic and Hygiene, Series A:Medical Microbiology, Infectious Diseases, Virology, Parasitology(1985), 259(2), 151-4.)

Exemplary Air-Diffusion Bioelectrocatalytic Cathode According theInvention:

Enzymes catalyze chemical reactions in aqueous environments.Consequently, conventional fuel cells that use enzymes as theircatalytic component measure performance of the device operating in anaqueous environment. For the cathode reaction, the concentration ofoxygen in a saturated aqueous solution is limited to 240 μM.Consequently, the power density of a fuel cell using a biocathode isoxygen limited. The air-diffusion bioelectrocatalytic cathode of theinvention, as describe herein, overcomes this limitation by enabling thebiocathode to be operated in humidified air or humidified oxygen.Furthermore, the air diffusion bioelectrocatalytical cathode accordingto the invention can be used for gas phase fuel cells operating undermild temperatures and pH.

Conventional systems include a laccase-based air cathode. However, inthe cathode system according to the invention, a polymer composite isused that comprises polypyrrole embedded with laccase and the redoxmediator, ABTS as the bioelectrocatalytic material. This materialperforms significantly better than prior art systems because ABTSfacilitates the kinetics of electron transfer between the cathode andthe active site of laccase. Broadly speaking, any redox-active monomeror polymer according to the invention can be used as thebioelectrocatalytic material as described herein. Polymer based systemswould usually be preferable over monomer based systems as leakage of amonomer mediator would reduce the lifetime of the air diffusionbioelectrocatalytical cathode. Any conducting polymer can fulfill therole described herein for polypyrrole. Other exemplary enzymes that canbe used with a cathode system of the invention include bilirubinoxidase, ceruloplasmin, ascorbate oxidase or copper oxidases as well asany enzyme capable of reducing oxygen to water or to peroxide. Moreover,the invention contemplates applications for a biosensor based onenzymatic catalysis. Such an exemplary enzyme-based biosensor of theinvention could function as a gas sensor and, thus, may be moresensitive, faster and accurate than a biosensor operating in solution.

A preferred embodiment of an air diffusion bioelectrocatalytical cathodeis the polypyrrole/ABTS/laccase (PAL) system described below, which isprovided by electrodeposition of PAL on Toray carbon paper.

A cathode according to the invention performs according to the Sandequation:

$\frac{{\tau}^{1/2}}{C^{*}} = {\frac{n\; {FAD}_{0}^{1/2}\pi^{1/2}}{2} = {85.5{nD}_{0}^{1/2}A}}$

Because C*, D₀ and A are constant, a higher current results in fasterelectrodeposition. By using the Sand equation given above, therelationship between current, time and coulombs passed during theelectrodeposition of PAL on carbon paper can be evaluated, as shown inFIG. 8.

Electrodeposition of a bioelectrocatalytic film was achieved byimmersing 2.25 cm² Toray carbon paper in an aqueous solution containing200 mM pyrrole, 25 mM ABTS and 6 mg/ml laccase and applying an oxidizingpotential. Conditions for electrodeposition were 400 micro-amperes (μA)constant current for 12.8 hours, resulting in a black film ofpolypyrrole embedded with ABTS and laccase (PAL). A SEM of a PALelectrode on Toray carbon paper is shown in FIG. 9.

A NAFION (E. I. du Pont de Nemours and Company, Wilmington, Del. 19898)membrane was pretreated prior to use in a fuel cell of the invention bysoaking in 1 M hydrochloric acid (H₂SO₄) overnight. The anode of thefuel cell of the invention was prepared by coating Toray carbon paperwith 0.5 mg/cm² platinum (Pt) (E-TEK 30% Pt on VULCAN 72, CabotCorporation, Boyertown, Pa. 19512) mixed with a 5% solution of NAFION(NAFION/carbon ratio was 1). Fuel (hydrogen) and oxidant (oxygen) weredelivered to the anode and cathode, respectively, as separate humidifiedstreams at room temperature. No liquid phase electrolyte occupied eitherchamber in the fuel cell of the invention. Different resistors were usedto evaluate the potential versus current density curve (FIG. 10 a) andthe power density versus potential curve (FIG. 10 b).

Exemplary Suspended Particle Devices (SPDs) According to the Invention:

One example of an SPD is a chromogenic, or “smart” window, which usesthe small light-absorbing microscopic particles of SPDs to enable thewindow to switch between opaque and clear states in a matter of seconds.The parts, that make up an SPD light-control windows include thefollowing as shown in FIG. 11: two panels of glass or plastic;conductive material (used to coat the panes of glass); suspendedparticle devices (millions of these black particles are placed betweenthe two panes of glass); liquid suspension or film (allows the particlesto float freely between the glass); and control device (automatic ormanual).

In an SPD window, millions of the SPDs are placed between two panels ofglass or plastic, which is coated with a transparent conductivematerial. When electricity comes into contact with the SPDs via theconductive coating, they line up in a straight line and allow light (andheat) to flow through. Once the electricity is taken away, they moveback into a random pattern and block light. When the amount of voltageis decreased, the window darkens until it is completely dark, after allelectricity is taken away.

Users apply a moderate amount of voltage to the conductive material onthe window panes through a control device. Several control methods areoffered with the SPD light-control windows, including remote andautomatic devices. The windows can be controlled manually with arheostat or remote. Or, photocells and other sensing devices could beused to control the level of light automatically. The invention alsocontemplates other devices or applications, besides windows, that can bebased on an SPD. The redox-active monomers described herein or polymersthereof such as, for example, ABTS monomers and polyABTS can be used inan SPD of the invention such as, for example, an SPD light-controlwindow. For example, an ABTS molecule can be doped inside a very thinlayer of conductive polymer by electropolymerization. Or, a thin film ofpolyABTS can be evaporated onto the optically transparent electrode. Or,the electrode can be modified with a monolayer of ABTS (a derivativecontaining a siloxane, chlorosilane, or other reactive functionalgroup).

Other exemplary devices of the invention that can comprise aredox-active monomer, polymer, co-polymer or device as described hereinare generally described by U.S. Pat. Nos. 6,900,923, 6,301,040 and6,897,997 as well as U.S. Publication Nos. 2003/0107797 and2004/0201001.

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While the present invention has been described in conjunction with apreferred embodiment, one of ordinary skill, after reading the foregoingspecification, will be able to effect various changes, substitutions ofequivalents, and other alterations to that set forth herein. It istherefore intended that the protection granted by Letters Patent hereonbe limited only by the definitions contained in the appended claims andequivalents thereof.

1. A redox-active, conducting polymer energy storage system, said systemcomprising: an electrode and a counter electrode, wherein said electrodecomprises a first conducting polymer and said counter electrodecomprises a second conducting polymer, wherein said first conductingpolymer is doped by at least one or more first redox-active compoundsand/or by a polymer and/or a co-polymer of said one or more firstredox-active compounds and said second conducting polymer is doped by atleast one or more second redox-active compounds and/or by a polymerand/or a co-polymer of said one or more second redox-active compounds,and wherein there is a potential difference between the dopant for theelectrode and the dopant for the counter electrode.
 2. The redox-active,conducting polymer energy storage system according to claim 1, whereinat least one of the dopant for the electrode and/or the dopant for thecounter electrode comprises a monomer, and/or a polymer and/or aco-polymer of a monomer, having the structure:

wherein R₁ and R₁′ are selected from the group consisting of MeO, EtO,COF₃, SO₄H, SO₃ ⁻, SO₃H, H, CHNO₄S₂F₃, C₅H₄N₂O₆S₂F₆, C₁₀H₁₀N₄S₂, CH₃,n-Bu, Cl, NH₂, EtN, Br, alkyl, ether, ester, sulfonate, ammonium,carboxylate, amine, phosphonate and any combination thereof; R₂ and R₂′are selected from the group consisting of MeO, EtO, COF₃, SO₄H, SO₃,SO₃H, H, CHNO₄S₂F₃, C₅H₄N₂O₆S₂F₆, C₁₀H₁₀N₄S₂, CH₃, n-Bu, Cl, NH₂, EtN,Br, alkyl, ether, ester, sulfonate, ammonium, carboxylate, amine,phosphonate and any combination thereof; R₃ and R₃′ are selected fromthe group consisting of MeO, EtO, COF₃, SO₄H, SO₃, SO₃H, H, CHNO₄S₂F₃,C₅H₄N₂O₆S₂F₆, C₁₀H₁₀N₄S₂, CH₃, n-Bu, Cl, NH₂, EtN, Br, alkyl, ether,ester, sulfonate, ammonium, carboxylate, amine, phosphonate and anycombination thereof; and R₄ and R₄′ are selected from the groupconsisting of MeO, EtO, COF₃, SO₄H, SO₃, SO₃H, CHNO₄S₂F₃, C₅H₄N₂O₆S₂F₆,C₁₀H₁₀N₄S₂, n-Bu, Cl, NH₂, EtN, Br, alkyl, ether, ester, sulfonate,ammonium, carboxylate, amine, phosphonate, CH₃, H, C₂H₅, C₄H₉, C₆H₅,C₈H₁₇, C₂H₅S, C₃H₇S, C₄H₈Br, C₁₀H₂₃N, C₂₀H₂₁N₂, C₁₈H₂₅N₂, C₂₁H₂₃N₂,C₃₁H₂₉N₂O₂, C₂₂H₂₅N₄, C₂₀H₂₅N₂, C₃H₇OS, unsaturated carbon monomers,olefins, halo-olefins, dienes, acetylenes, styrenes, vinyl compounds,acrylic acids, acrylics, ring monomers, cyclic ethers, lactones,lactams, cyclic amines, cyclic sulfides, cyclic carbonates, cyclic acidanhydrides, cyclic iminoethers, amino acid N-carboxy anhydrides, cyclicimides, phosphorus containing cyclic compounds, silicon containingcyclic compounds, cyclic olefins, bifunctional monomers, phenols,melamines, ureas, diamines, dicarboxylic acids, hydroxy acids, oxycarboxylic acids, amino acids, amino carboxylic acids, diols,diisocyanates, sulfur containing compounds, phosphorus containingcompounds, aromatic ethers, dihalides, dihalogenated compounds,aldehydes, diketones and carbonates, carbonic acid derivatives,anilines, silane compounds and any combination thereof; wherein only oneof R₄ and R₄′ can be selected from the group consisting of CH₃, H, C₂H₅,C₄H₉, MeO, EtO, COF₃, SO₄H, SO₃, SO₃H, CHNO₄S₂F₃, C₅H₄N₂O₆S₂F₆,C₁₀H₁₀N₄S₂, n-Bu, Cl, NH₂, EtN, Br, alkyl, ether, ester, sulfonate,ammonium, carboxylate, amine, phosphonate and any combination thereof.3. The redox-active, conducting polymer energy storage system accordingto claim 2, wherein, in said monomer: R₁ and R₁′ are selected from thegroup consisting of MeO, Eta, COF₃, SO₄H, SO₃ ⁻, SO₃H, H, CHNO₄S₂F₃,C₅H₄N₂O₆S₂F₆, C₁₀H₁₀N₄S₂, CH₃, n-Bu, Cl, NH₂, EtN, Br, alkyl, ether,ester, sulfonate, ammonium, carboxylate, amine, phosphonate and anycombination thereof; R₂ and R₂′ are H; R₃ and R₃′ are H; and R₄ and R₄′are selected from the group consisting of MeO, EtO, COF₃, SO₄H, SO₃,SO₃H, CHNO₄S₂F₃, C₅H₄N₂O₆S₂F₆, C₁₀H₁₀N₄S₂, n-Bu, Cl, NH₂, EtN, Br,alkyl, ether, ester, sulfonate, ammonium, carboxylate, amine,phosphonate, CH₃, H, C₂H₅, C₄H₉, C₆H₅, C₈H₁₇, C₂H₅S, C₃H₇S, C₄H₉Br,H₂₃N, C₂₀H₂₁N₂, C₁₈H₂₅N₂, C₂₁H₂₃N₂, C₃₁H₂₉N₂O₂, C₂₂H₂₅N₄, C₂₀H₂₅N₂,C₃H₇OS, unsaturated carbon monomers, olefins, halo-olefins, dienes,acetylenes, styrenes, vinyl compounds, acrylic acids, acrylics, ringmonomers, cyclic ethers, lactones, lactams, cyclic amines, cyclicsulfides, cyclic carbonates, cyclic acid anhydrides, cyclic iminoethers,amino acid N-carboxy anhydrides, cyclic imides, phosphorus containingcyclic compounds, silicon containing cyclic compounds, cyclic olefins,bifunctional monomers, phenols, melamines, ureas, diamines, dicarboxylicacids, hydroxy acids, oxy carboxylic acids, amino acids, aminocarboxylic acids, diols, diisocyanates, sulfur containing compounds,phosphorus containing compounds, aromatic ethers, dihalides,dihalogenated compounds, aldehydes, diketones and carbonates, carbonicacid derivatives, anilines, silane compounds and any combinationthereof; wherein only one of R₄ and R₄′ can be selected from the groupconsisting of CH₃, H, C₂H₅, C₄H₉, MeO, EtO, COF₃, SO₄H, SO₃ ⁻, SO₃H,CHNO₄S₂F₃, C₅H₄N₂O₆S₂F₆, C₁₀H₁₀N₄S₂, n-Bu, Cl, NH₂, EtN, Br, alkyl,ether, ester, sulfonate, ammonium, carboxylate, amine, phosphonate andany combination thereof.
 4. The redox-active, conducting polymer energystorage system according to claim 1, wherein said energy storage systemis a battery.
 5. The redox-active, conducting polymer energy storagesystem according to claim 1, wherein said energy storage system is acapacitor.
 6. The redox-active, conducting polymer energy storage systemaccording to claim 2, wherein at least one of the dopant for theelectrode and/or the dopant for the counter electrode comprises aco-polymer of said monomer and acrylic acid.
 7. The redox-active,conducting polymer energy storage system according to claim 2, whereinat least one of the dopant for the electrode and/or the dopant for thecounter electrode comprises a co-polymer of said monomer and 1-vinylimidazole.
 8. The redox-active, conducting polymer energy storage systemaccording to claim 1, wherein at least one of the dopants for theelectrode is 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonate) andwherein at least one of the dopants for the counter electrode is indigocarmine.
 9. The redox-active, conducting polymer energy storage systemaccording to claim 8, wherein at least one of the first conductingpolymer and the second conducting polymer is an organicpolyheterocyclic.
 10. The redox-active, conducting polymer energystorage system according to claim 9, wherein at least one of the firstconducting polymer and the second conducting polymer is selected fromthe group consisting of polypyrrole, polythiophene, polyaniline andderivatives thereof.
 11. The redox-active, conducting polymer energystorage system according to claim 10, wherein at least one of the firstconducting polymer and the second conducting polymer is polypyrrole. 12.The redox-active, conducting polymer energy storage system according toclaim 1, wherein at least one of the first conducting polymer and thesecond conducting polymer is an organic polyheterocyclic.
 13. Theredox-active, conducting polymer energy storage system according toclaim 12, wherein at least one of the first conducting polymer and thesecond conducting polymer is selected from the group consisting ofpolypyrrole, polythiophene, polyaniline and derivatives thereof.
 14. Theredox-active, conducting polymer energy storage system according toclaim 13, wherein at least one of the first conducting polymer and thesecond conducting polymer is polypyrrole.